Field of the Invention
The present invention relates to a heat exchanger.
Discussion of the Background
For example, a condenser of a car air conditioner has been demanded to be further improved in refrigerant condensation efficiency and refrigerant subcooling efficiency. In order to meet such a demand, the applicant of the present application has proposed an improved condenser (see the pamphlet of WO2010/047320). The proposed condenser has a condensation section and a subcooling section provided such that the condensation section is located on the upper side. The condenser includes a plurality of heat exchange tubes, corrugated fins, and header tanks. The heat exchange tubes are disposed in parallel such that their longitudinal direction coincides with the left-right direction and they are spaced apart from one another in the vertical direction. Each of the corrugated fins has crest portions extending in an air-passing direction, trough portions extending in the air-passing direction, and connection portions connecting the crest portions and the trough portions. Each of the corrugated fins is disposed between adjacent heat exchange tubes. The header tanks are disposed such that their longitudinal direction coincides with the vertical direction, and left and right end portions of the heat exchange tubes are connected to the corresponding header tanks. Three heat exchange paths each composed of a plurality of heat exchange tubes successively arranged in the vertical direction are juxtaposed in the vertical direction. The condenser has a first tube group composed of the heat exchange path at the upper end, and a second tube group provided below the first tube group and composed of the remaining heat exchange paths. The heat exchange tubes of the second tube group are greater in length than the heat exchange tubes of the first tube group. The header tanks include a first header tank and a second header tank provided at the left end or right end. The heat exchange tubes which form the heat exchange path of the first tube group are connected to the first header tank, and the heat exchange tubes which form the heat exchange paths of the second tube group are connected to the second header tank. The second header tank is disposed on the outer side of the first header tank with respect to the left-right direction, and the upper end of the second header tank is located above the lower end of the first header tank. Refrigerant is caused to flow through the heat exchange paths of the second tube group after flowing through the heat exchange path of the first tube group. The second header tank has a function of separating gas and liquid from each other and storing the separated liquid. The heat exchange path of the first tube group and the upper end heat exchange path of the second tube group serve as refrigerant condensation paths present in the condensation section, and the remaining heat exchange path of the second tube group serves as a refrigerant subcooling path present in the subcooling section.
In the condenser disclosed in the pamphlet, the length of the heat exchange tubes of the lower end refrigerant condensation path of the second tube group and the length of the heat exchange tubes of the refrigerant subcooling path of the second tube group can be rendered greater than the length of the heat exchange tubes of the first tube group. Therefore, the areas of the heat exchange sections of the condensation section and the subcooling section increase. As a result, the refrigerant condensation efficiency and the refrigerant subcooling efficiency can be improved further.